Here is how Time summarized how Obama described his drug use in his autobiography....

In his signature style of honesty bordering on self-deprecation, Obama candidly admits to drug and alcohol use in his younger years. Calling himself a "pothead" heading towards "the final, fatal role of the young would-be black man," Obama confesses to getting high in order to "push questions of who I was out of my mind." (p. 93) He cites using marijuana and cocaine, but he explicitly assures his readers that he did not use crack.(p. 93)

“Pot had helped, and booze; maybe a little blow when you could afford it,” Obama speculated in his autobiography. “Not smack, though - Dr. Benway, my potential initiator, had been just a little too eager for me to go through with that. Said he could do it blindfolded, but he was shaking like a faulty engine when he said it….Junkie Pothead.”

Not sure of the accuracy of the above quote, but I know the "Not smack, though" line is accurate.

Daily polling and focus group testing told them that this was a big tactical mistake. Her numbers were tanking, and issuing an apology along making a head roll was the only thing that seemed to staunch the hemmoraging.